A cutting insert capable of performing chip control over a wide range from the above-described medium cutting to the finish cutting has been proposed, for example, in Patent Document 1. In the cutting insert, a breaker groove along a cutting edge is formed on a rake face, and a protrusion on a boss surface extends at a corner edge of the cutting edge. The leading end of the protrusion assumes a concave shape so as to enclose the corner edge, when viewed from above. An erecting surface with an erecting angle of 10° to 30° which projects from two top portions of the thus concaved protrusion to the vicinity of the cutting edge so as to be the longest length is formed at the cutting insert. The erecting surface is formed so as to be further away from the cutting edge, as the erecting surface extends away from the corner edge.
Further, particularly, in order to control chips during finish cutting in which depth of the cut is small, the cutting insert proposed in Patent Documents 2 and 3 is provided with an indentation near a corner edge on a rake face. At a region opposite to the corner edge of the indentation, an inclined surface which serves as a breaker and a rib are provided.
Prior Art Documents
Patent Documents
Patent Document 1: Japanese Published Unexamined Patent Application No. 2006-272548
Patent Document 2: Japanese Patent No. 2966007
Patent Document 3: Japanese Published Unexamined Patent Application No. 2004-216510